"""                         # 注释开始
    bar(x[, y])               # 原型简述

Compute the Bar index between `x` and `y`. If `y` is missing, compute
the Bar index between all pairs of columns of `x`.

# Examples                  # 一级标题
```julia-repl                  # 代码区开始，并紧随Markdown式的语言标识文字
julia> bar([1, 2], [1, 2])
1
```                         # 代码区结束
"""                         # 注释结束
function bar(x, y) ...
